A Review of the Effects and Economic Impact of Aflatoxins

Abstract

Aflatoxins, or extremely toxic mycotoxin contaminates, need to be carefully monitored due to food safety hazards. Therefore, it is important to catch aflatoxins and determine their origin as quick and precise as possible (Wei, T., Chen, Z., Li, G., & Zhang, Z., 2018). A variety of Aspergillus fungi ae responsible for producing the aflatoxins (National Biomonitoring Program, 2017). Aflatoxins are one of the most studied mycotoxins due to their powerful “carcinogenic effect in susceptible laboratory animals and their acute toxicological effects in humans” (Department of Animal Science). There are still no methods to completely rid foods form aflatoxins; therefore, many countries are working to develop ways to test for aflatoxins and place rigid limits on crops used for food or animal feed (Department of Animal Science). Aflatoxins can be consumed; however, larger doses can cause various illnesses and/or death. Providing a limit on the amount of aflatoxin in food and feed will reduce the amounts humans and animals ingest.

Overview

Aflatoxin is a fungal toxin that contaminates crops like corn. A variety of Aspergillus fungi produce aflatoxins. An aflatoxin contamination can take place during the harvesting, production, storing, or processing of a crop. Both humans and animals exposed to aflatoxins can develop serious illnesses or even death. Humans can even be negatively affected by consuming animals that have ingested aflatoxins (CDC – Health Studies Program: Chemical Exposures – Aflatoxin).  Humans exposed to aflatoxins in high doses for long periods of time can develop both chronic and acute hepatocellular injury, as well as, liver failure and death (National Biomonitoring Program, 2017). In Kenya, 40 percent of acute aflatoxin poisoning cases result in death (CDC – Health Studies Program: Chemical Exposures – Aflatoxin).

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Aflatoxins have also shown carcinogenic effects. AFM1, or aflatoxin M1, is a toxic secondary metabolite that comes from AFB1. AFB1 is one derivative from aflatoxins. AFB1 is then bio-transformed into AFM1. Both AFB1 and AFM1 are carcinogenic, yet AFM1 is typically secreted into milk and other food products. The International Agency for Research on Cancer categorizes this secondary metabolite as a group 1 carcinogen. AFM1 is considered a food safety risk if consumed (Sulzberger, S. A., Melnichenko, S., & Cardoso, F. C., 2017).

Aflatoxin exposure is common in Africa, especially throughout Sub-Saharan Africa. Aflatoxins have been found in many of their cereal crops. Those cereal crops were linked to impairments in the growth of children. One group studied African infants from birth to the age of two. The study found a significant effect of exposure to aflatoxin on their growth (Watson, S., Moore, S. E., Darboe, M. K., Chen, G., Tu, Y.-K., Huang, Y.-T., … Gong, Y. Y., 2018). This study is significant because it suggests that growth impairment in children could be linked to aflatoxin exposure. Aflatoxins have also been linked to various diseases like aflatoxicosis. Aflatoxicosis can affect both animals and humans. Based off geographical location and certain environmental factors, aflatoxin occurrence will differ (Department of Animal Science). Whether aflatoxins do appear in crops is based on many factors. Temperature and humidity are major aspects that determine aflatoxin outbreaks (Watson, S., Moore, S. E., Darboe, M. K., Chen, G., Tu, Y.-K., Huang, Y.-T., … Gong, Y. Y., 2018).

Detection and Testing of Aflatoxins

Countries that are considered developed regularly test for aflatoxin using various detection procedures in laboratory settings. There are specific aflatoxin restrictions set up in order to determine safe human or animal consumption limits. If the tests are over the specified limit, the food must be destroyed and disposed of. However, in many developing countries, crops are not regularly tested for aflatoxin. Numerous people grow their own crops at home and fail to recognize the potential dangers of aflatoxin poisoning. They also lack the means of testing for it. If the crops are not properly harvested, stored, or processed, aflatoxin-producing fungi can contaminate the crops. “As a result, an estimated 4.5 billion people living in developing countries may be chronically exposed to aflatoxin through their diet” (CDC – Health Studies Program: Chemical Exposures – Aflatoxin).

One study designed a “porous monolithic column based on covalent cross-linked polymer gels for online extraction and analysis of trace aflatoxins in food samples with complicated matrices coupled with high-performance liquid chromatography-ultraviolet detector (HPLC-UV). The prepared monolithic column showed excellent enrichment performance due to its good permeability, good reproducibility and long-life span. The study of adsorption mechanism suggested that the excellent enrichment performance of this monolithic column was attributed to the multiple effect of π-π stacking interaction, hydrophobic effect and steric effect.” (Wei, T., Chen, Z., Li, G., & Zhang, Z., 2018). When used contaminated food samples, aflatoxins G1 and B1 could be found and quantified. Their technique proved to be a capable means to analyze traces of aflatoxins in complex food samples.

LFI, or lateral flow immunoassay, is one technique used for testing aflatoxins. It is time efficient, cheap, and easy to use. The lateral flow immunoassay has the ability to detect foodborne pathogens, mycotoxins, metal ions, and antibiotics (Chun Wang, Juan Peng, Dao-Feng Liu, Ke-Yu Xing, Gang-Gang Zhang, Zhen Huang, … Wei Hua Lai., 2018). The LFI can be adjusted to detect aflatoxins in crops.  The study New tools to screen wild peanut species for aflatoxin accumulation and genetic fingerprinting worked by using a set of tools that would screen peanuts seeds for aflatoxins. The method is also cost-efficient. Their method recorded the genetic fingerprint by using a singular peanut seed analysis. The method was proficient in testing for a combination of very informative markers in screening (Arias, R. S., Sobolev, V. S., Massa, A. N., Orner, V. A., Walk, T. E., Ballard, L. L., … Seijo, G.J., 2018).

Outbreaks

Corn is one of the largest crops at risk for contracting aflatoxins since it is typically grown in humid climates. Corn is often contaminated with reoccurring aflatoxin outbreaks. This is problematic because it is one of the most stable crops for many countries. Aflatoxins are typically stable in most foods, yet certain processes can cause them to become unstable and cause aflatoxin M1. Aflatoxin-contaminated corn and cottonseed meal used in cattle feed often causes AFM1 contaminated milk or milk products (Karlovsky, P., Suman, M., Berthiller, F., De Meester, J., Eisenbrand, G., Perrin, I., Oswald, I. P., Speijers, G., Chiodini, A., Recker, T., … Dussort, P., 2016).

Many outbreaks dealing with aflatoxins originate from corn. Kenya has had numerous issues with acute aflatoxicosis outbreaks. Aflatoxin contamination was a recurrent problem in their homegrown corn. Multiple CDC teams have worked with Kenyan Ministries of Health to help screen for aflatoxins. The CDC teams used rapid, portable aflatoxin screening tools that could be used in the field to determine if the corn was contaminated. They also worked to guide “urgent maize replacement efforts” during outbreaks. The CDC teams used portable lateral flow immunoassay to test for the aflatoxins. Theportable lateral flow immunoassay is a test that can be used at commercial silo laboratories. Mobile labs were set up in each village. There, they would grind and test corn samples. The test had to be altered for use in areas of Kenya that lacked electricity or refrigeration. CDC’s field screening methods showed a sensitivity of 98% and specificity of 91% (CDC – Health Studies Program: Chemical Exposures – Aflatoxin., 2012). They were able to effectively and quickly receive results.

In 2004, Kenya experienced an outbreak of jaundice with a high case-fatality rate. The initial lab tests of food from affected areas in Kenya revealed high amounts of aflatoxins. These high levels suggested that the outbreak was from aflatoxin poisoning. Aflatoxin concentrations are limited to 20 parts per billion in the United States. Kenyan authorities have since adopted the same concentration. The widespread aflatoxin contamination all sourced from locally grown corn due to damp storage conditions. In order to combat the aflatoxin-contaminated corn, it was replaced with noncontaminated corn. However, despite all efforts, new cases of aflatoxin poisoning still arose. Aflatoxin poisoning will remain a problem until proper storage methods are implemented to keep corn dry. Improved testing methods will also help with aflatoxin outbreaks. Commercially sold and bought corn should also be tested for aflatoxins in order to improve public health (Outbreak of Aflatoxin Poisoning — Eastern and Central Provinces, Kenya, January–July 2004).

Management of Aflatoxins

In order to protect humans and animals against harmful aflatoxins, over 100 countries have created a maximum tolerable level standard for aflatoxins in food.Global impacts of aflatoxin in maize: Trade and human health detailed, “some nations have set standards for the most toxic and carcinogenic of the aflatoxins, aflatoxin B1 (AFB1); others regulate ‘total aflatoxins’ (the sum of the concentrations of aflatoxin B1, B2, G1, and G2); and others have standards for both AFB1 and total aflatoxins in foodstuffs. Additionally, several nations have set standards for aflatoxin M1 (AFM1): the metabolite of aflatoxin B1, which can be found in dairy products due to dairy animals’ consumption of aflatoxin-contaminated feed” (Wu, F. 2015). It is important the regulate the levels of aflatoxins in food. This is necessary if countries hope to control aflatoxin poisoning. However, despite any regulations a nation may have to regulate aflatoxins, many foods are not tested. This is extremely common in areas that use subsistence farming (Wu, F. 2015).

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Proper food harvesting, storage practices, and regulations are all essential to prevent exposure to the harmful aflatoxins.  Giving oral clay supplements to animals has shown to reduce the toxicity of aflatoxins found in contaminated feeds (Sulzberger, S. A., Melnichenko, S., & Cardoso, F. C., 2017). The study Effects of dietary adsorbent on milk aflatoxin M1 content and the health of lactating dairy cows exposed to long-term aflatoxin B1 challenge used Solis Mos, a clay-based mineral, in the diet of dairy cows exposed to aflatoxins. The study found that “long-term ingestion of adsorbent Solis Mos did not affect DMI, lactation performance, or liver function of early- to mid-lactation dairy cows”.  The Solis Mos reduced the AFM1 concentrations in the milk, and it also enhanced the ruminal fermentation and immunological condition in dairy cows exposed to AFB1 (Xiong, J. L., Wang, Y. M., Zhou, H. L., & Liu, J. X. (2018). Solis Mos reduced harmful aflatoxin derivatives in milk. Feeding dairy cattle clay supplements could reduce aflatoxin poisoning as well.

NovaSil is another type of clay-based supplement that could potentially be used to prevent diseases and fatalities caused by aflatoxicosis. “Ideally, the best long-term solution would be to reduce aflatoxin contamination in maize and groundnuts through improved harvesting, drying, and storage techniques; genetically modified crops; or application of nontoxic fungi to reduce the growth of aflatoxin” (CDC – Health Studies Program – Success Stories – CDC Awards HSB iFund Challenge for Innovation, 2013). The issue with the NovaSil is applying it at a large scale. More pilot tests using NovaSil will be necessary before it can be used. If the tests go well using NovaSil, it could save thousands from the harmful effects of aflatoxins (CDC – Health Studies Program – Success Stories – CDC Awards HSB iFund Challenge for Innovation, 2013).

Economic Impact

 For many, it can be an economic burden to have properly prevent aflatoxins. Since it can be expensive, many people fail to take the preventative measures necessary. This leads to a higher risk for long periods of exposure to the harmful aflatoxins, which puts large ammounts of people at risk (CDC – Health Studies Program – Success Stories – CDC Awards HSB iFund Challenge for Innovation, 2013). Aflatoxins also levy great burdens on the corn trade. One study found that the total costs of aflatoxin in the United States to be around $500 million annually. This includes the loss of crops, as well as, through animal health effects. Another study estimated a loss of $163 million annually of corn crops to aflatoxins. Corn that is rejected as human food can be used for animal feed though. Costs to manage aflatoxins, in the United States alone, range from $20-50 million per year (Sulzberger, S. A., Melnichenko, S., & Cardoso, F. C., 2017).

Conclusion

Aflatoxins can cause cancer, immunosuppression, growth stunting in children, acute aflatoxicosis, which can cause jaundice, vomiting, liver failure, and death, and affect the body’s ability to absorb proper nutrients (CDC – Health Studies Program – Success Stories – CDC Awards HSB iFund Challenge for Innovation 2013). There are still no stable aflatoxin resistant cultivars that exist (Arias, R. S., Sobolev, V. S., Massa, A. N., Orner, V. A., Walk, T. E., Ballard, L. L., … Seijo, G.J., 2018). Therefore, it is necessary to use an effective technique to screen and test for aflatoxins. Proper crop techniques fight against harmful aflatoxin contaminations as well. The National Biomonitoring Program considers aflatoxins to be unavoidable contaminants in our country’s food supply (CDC – Health Studies Program: Chemical Exposures – Aflatoxin, 2012). Screening for aflatoxins is essential, as well as, taking proper preventative measures against the toxins.  

References

• Arias, R. S., Sobolev, V. S., Massa, A. N., Orner, V. A., Walk, T. E., Ballard, L. L., … Seijo, G.              J. (2018). New tools to screen wild peanut species for aflatoxin accumulation and genetic              fingerprinting. BMC Plant Biology, 18(1), 170. https://doi.org/10.1186/s12870-0181355-9
• CDC – Health Studies Program: Chemical Exposures – Aflatoxin. (2012, January 13). Retrieved              December 1, 2018, from https://www.cdc.gov/nceh/hsb/chemicals/aflatoxin.htm
• CDC – Health Studies Program – Success Stories – CDC Awards HSB iFund Challenge for Innovation. (2013, August 12). Retrieved December 4, 2018, from https://www.cdc.gov/nceh/hsb/success_stories/ifund.htm
• Chun Wang, Juan Peng, Dao-Feng Liu, Ke-Yu Xing, Gang-Gang Zhang, Zhen Huang, … Wei Hua Lai. (2018). Lateral flow immunoassay integrated with competitive and sandwich models for the detection of aflatoxin M1 and Escherichia coli O157:H7 in milk. Journal of Dairy Science, 101(10), 8767–8777. https://doi.org/10.3168/jds.2018-14655
• Department of Animal Science – Plants Poisonous to Livestock. (n.d.). Retrieved December 1, 2018, from https://poisonousplants.ansci.cornell.edu/toxicagents/aflatoxin/aflatoxin.html
• Karlovsky, P., Suman, M., Berthiller, F., De Meester, J., Eisenbrand, G., Perrin, I., Oswald, I. P.,              Speijers, G., Chiodini, A., Recker, T., … Dussort, P. (2016). Impact of food processing and detoxification treatments on mycotoxin contamination. Mycotoxin research, 32(4), 179-205.
• National Biomonitoring Program. CDC. (2017, April 07). Retrieved December 2, 2018, from https://www.cdc.gov/biomonitoring/toxins.html
• Outbreak of Aflatoxin Poisoning — Eastern and Central Provinces, Kenya, January–July 2004. (2004, September 3). Retrieved December 1, 2018, from https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5334a4.htm
• Sulzberger, S. A., Melnichenko, S., & Cardoso, F. C. (2017). Effects of clay after an aflatoxin challenge on aflatoxin clearance, milk production, and metabolism of Holstein cows. Journal Of Dairy Science, 100(3), 1856–1869. https://doi.org/10.3168/jds.2016-11612
• Watson, S., Moore, S. E., Darboe, M. K., Chen, G., Tu, Y.-K., Huang, Y.-T., … Gong, Y. Y. (2018). Impaired growth in rural Gambian infants exposed to aflatoxin: a prospective              cohort study. BMC Public Health, 18(1), 1247.  https://doi.org/10.1186/s12889-018-61644
• Wei, T., Chen, Z., Li, G., & Zhang, Z. (2018). A monolithic column based on covalent cross-linked polymer gels for online extraction and analysis of trace aflatoxins in food sample. Journal of Chromatography. A, 1548, 27–36. https://doi.org/10.1016/j.chroma.2018.03.015
• Wu, F. (2015, May 3). Global impacts of aflatoxin in maize: Trade and human health. Retrieved              November 30, 2018, from https://www.wageningenacademic.com/doi/pdf/10.3920/WMJ2014.1737
• Xiong, J. L., Wang, Y. M., Zhou, H. L., & Liu, J. X. (2018). Effects of dietary adsorbent on milk aflatoxin M1 content and the health of lactating dairy cows exposed to long-term aflatoxin B1 challenge. Journal of Dairy Science, 101(10), 8944–8953. https://doi.org/10.3168/jds.2018-14645